FOLDS AND FAULTING. 463 



tion and depression, such movements not being continuous 

 on the same spot (as with folds), but ofttimes developing 

 more rapidly than folding, and that these areas of move- 

 ment, or, as he terms them, Domes, are the originating 

 cause of most normal faults, which are therefore due as 

 much to elevation as depression. 



The year 1892 has been conspicuous in the annals of 

 tectonic geology, the works of Lapworth, Bertrand, and the 

 publication of the second edition of Suess' Antlitz der 

 Ei'de, marking prominently the direction along which the 

 tendencies of geo-tectonic conceptions are proceeding, and 

 in this same year Bertrand (14) reviewed mountain struc- 

 ture as a whole. 



RecoenisinCT mountains to be folded zones of the earth's 

 crust, he lays special stress upon the continuity of such 

 regions throughout the old continent, and argues that they 

 are the result of the crushing of wedges of the earth's 

 sphere. He notes that in Eurasia three marked regions or 

 belts have been traced out, the most ancient being the one 

 nearest to the pole ; of these belts, in the most southerly 

 (the Alpino- Himalayan), even the Miocene strata have been 

 affected by the movement ; south of the line of coal mea- 

 sures, extending from Wales to Westphalia, is a second 

 belt, in which all the palaeozoic rocks are folded, and, north 

 of that same line, a still older one, in which only the pre- 

 Devonian have undergone that process. He therefore 

 concludes that the oldest zones are those nearest to the 

 pole, and, from the discordance observed in the most ancient 

 series of rocks in the northern regions, is of opinion that 

 it was in the polar regions that occurred the first dislocations 

 of the earth's crust, and that at a period of time, possibly, 

 preceding the appearance of life upon the globe. He is 

 further of opinion that the folding movement, which has 

 been active throughout long periods, has been gradually 

 shifting towards the equator, the most recent chains 

 due to this movement forming an almost continuous belt 

 around the globe, whilst the more ancient form a series 

 of roughly concentric belts approaching nearer and nearer 

 to the pole. He recognises, however, that, whilst these 



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